Japanese perch are greenish with red pelvic, anal and caudal fins.

Juveniles feed on zooplankton, bottom invertebrate fauna, other fish fry, scuds, small shrimp and insects, while adults feed on both invertebrates and smaller fish, mainly Japanese rice fish, Japanese minnows (Nipponocypris temminckii, Rhynchocypris spp., Gnathopogon elongatus), Japanese smelt (Hypomesus nipponensis) fry, small crayfish and tadpoles.

Japanese perch start eating other fish when they reach a size of around 6 cm (2.4 in).

The primary spawning season for the Japanese perch occurs from the middle of April through approximately June, depositing their eggs on water plants or the branches of trees or shrubs immersed in the water.

[citation needed] The Japanese perch is a frequent prey of many fish-eating predators, such as the great cormorant and common kingfisher.